The embodiments of the present inventive concept relate to semiconductor devices and methods of forming the semiconductor devices and, more particularly, to nonvolatile memory devices and methods of forming the nonvolatile memory devices.
Generally, semiconductor memory devices may be categorized into volatile memory devices which lose data upon power-off and nonvolatile memory devices which retain data when power is last. Flash memory devices are included in the nonvolatile memory devices. The flash memory devices are highly integrated devices which include erasable programmable read only memories (EPROMs) and electrically erasable programmable read only memories (EEPROMs). The flash memory devices may be classified into a NOR type and a NAND type. The NAND type flash memory devices are formed in strings and have higher density integration as compared to NOR type flash memory devices.